Optical packet switching (OPS) is a promising technology to handle the exponential growth of the internet. It is desirable for photonic elements to operate over large wavelength ranges with low polarization crosstalk. Elements such as directional couplers may be used in a photonic switching fabric in OPS.
Optical devices may be integrated in a photonic integrated circuit (PIC) containing optical waveguides. Optical waveguides are light conduits that contain a slab, strip, or cylinder of a dielectric material surrounded by another dielectric material having a lower refractive index. The light propagates along, and is confined to, the higher refractive index material through total internal reflection. In a PIC, the core may be silicon, surrounded by a lower refractive index material, such as silicon dioxide, silicon nitride, silicon oxynitride, and/or air. The waveguides may be a single mode or multi-mode waveguide. In an example, a PIC operates at a telecommunications waveband, such as 1550 nm or 1310 nm. The light may be coupled into, out of, or between optical waveguides. In a PIC, multiple photonic functions are integrated on a substrate, such as silicon-on-insulator (SOI). PICs are used for optical communications, and for other applications, such as biomedical applications and photonic computing. PICs may provide increased functionality, while being compact, and enabling higher performance than discrete optical devices.